Vancouver Island residents reported houses rattling after an earthquake struck shortly after 6 p.m. PT Wednesday.

The 4.8 magnitude quake hit 18 kilometres east-northeast of Tofino, B.C., at a depth of 24 kilometres.

A tsunami is not expected and there were no reports of damage.

Residents in Courtenay, Campbell River and Qualicum Beach reported beds shaking and dishes rattling in their cupboards.

"Staying in a log cabin in Tofino and we thought a truck had hit something," tweeted one resident.

Hayes Bishop, who works at Middle Beach Lodge in Tofino, said the shaking lasted for about 20 seconds.

"I felt some vibrations and I looked up and I was able to see the window shaking," he said. "Yeah, you could definitely feel it."

"Quite a few of the guests came downstairs to ask if that was indeed an earthquake, and there is definitely some cause for concern because we are very close to the ocean here."

The quake was also felt in the Gulf Islands and as far away as the Lower Mainland, according to some reports.

Earthquake latest in a series

Wednesday's shaker is the latest in a series of recent quakes that have struck off the B.C. coast.

Last Friday and Saturday separate earthquakes with respective magnitudes of 5.2 and 4.5 struck 200 km off the coast of Port Hardy at the northern end of Vancouver Island.

Earthquake cluster

A map of the Pacific Ocean off the north coast of Vancouver Island showing a cluster of eight earthquakes over the last month ranging in magnitude from 4.0 to 5.2 at depths ranging from 10 to 22 km. (earthquaketrack,com)

A swarm of five earthquakes also struck west of Port Hardy further in late December, at depths ranging from 10 to 22 km.

According to the Geological Survey of Canada, these clusters are larger than normal, but not unusual, nor does it effectively increase the risk of the "big one."

CBC meteorologist Johanna Wagstaffe said Wednesday night's quake likely occurred within the overriding North America plate.

The smaller quakes can sometimes be damaging because of the shallow depth, she said, even though the recent ones in the past month haven't fit that characterization.

Wagstaffe said the "big one," a damaging megathrust earthquake, will occur within the Juan de Fuca plate which has become stuck trying to move under the North American plate. She said these are at two very different locations.

Earthquake plate tectonics

In this graphic, provided by CBC metereologist Johanna Wagstaffe, the Juan de Fuca plate is moving toward and riding under the North America plate. Wagstaffe says earthquakes on the North American plate are in a completely different location from the Juan de Fuca plate. (CBC)